Stroke is one of the leading causes of death and a major cause of disability in the world. Large prospective epidemiologic studies have provided evidence that nutritional factors are important modifiable risk factors for stroke. Identification of a novel protective dietary factor may improve stroke prevention and enhance our understanding of the pathophysiology. Taurine, a derivative of the sulfur-containing (sulfhydryl) amino acid cysteine, is a conditionally essential amino acid. Because humans are unable to synthesize more than minor quantities of taurine, it is mostly obtained from diet, mainly seafood and the dark meat of poultry. Animal and experimental studies have suggested that taurine may protect against stroke because of its antioxidant, anti-hypertension, and anti-inflammatory activity. However, prospective epidemiologic studies of taurine and stroke are lacking. We propose to conduct a prospective case-control study of the risk of stroke nested in the New York University Women's Health Study (NYUWHS). The NYUWHS is a prospective cohort study of 14,274 healthy women 34 to 65 years old with blood samples collected at multiple times and comprehensive follow-up for disease outcomes. In a case-control study of coronary heart disease nested in the NYUWHS, we found that serum levels of taurine were significantly associated with a reduced risk of coronary heart disease among women with a high level of serum cholesterol at baseline. In addition, high levels of serum taurine were related to a significant reduced risk of hypertension. On the basis of these findings, we propose to examine the association between serum taurine levels and subsequent stroke risk. Serum taurine will be measured in up to three serum samples collected over time for each individual. The proposed project will be the first prospective study of taurine and stroke risk. The project has great potential of addressing an important public health topic in cardiovascular epidemiology.